The present disclosure relates generally to a mold, and more particularly, to a plastic injection mold, and an associated molding system and method for producing a molded part with undercuts removed from a mold with little or no permanent deformation. The molded part may be a vehicle bumper fascia.
Plastic molding is a commonly employed technique for producing parts of simple to complex geometry and may include, without limitation, techniques such as compression molding, injection molding, roto-molding, etc. Injection molding is a popular technique for producing large-scale parts, such as vehicle parts. Injection molding typically utilizes a mold that is divided into two mold halves, for example, one half including a mold cavity and another including a mold core. One half of the mold is affixed to a stationary molding machine platen and the other half is affixed to a moving molding machine platen.
Without limitation, one such part and a part of particular interest in the present disclosure, is a vehicle bumper fascia. As would be well known to one of skill in the art, vehicle bumper fascias are commonly injection molded from various plastic materials. These bumper fascias have a forward or rearward facing surface whose length extends in a width direction along a corresponding front or rear portion of a vehicle, as well as wing sections that extend transversely in the length direction of the vehicle, typically to form a portion of the wheel wells on a vehicle.
Such bumper fascias are typically formed using large injection molds divided into a mold cavity and a primary mold core that cooperate when the mold is closed to form the molded bumper fascia. Secondary cores may also be present. The wing portions of the bumper fascia typically terminate in substantially arch-shaped ends so as to form a portion of what is normally a like-shaped wheel well. These arch-shaped wheel well forming portions of a bumper fascia typically include a flange that extends transversely inward to facilitate attachment of the wing end portion of the bumper fascia to the vehicle body, e.g., via screws or other fasteners.
As one skilled in the art of molding would clearly understand, the inwardly extending flanges of the bumper fascia wheel well portions cannot be molded by a mold having only a typical cavity and stationary core, as creation of the flanges requires an undercut in the mold cavity that would subsequently prevent removal of the bumper fascia after molding. Consequently, as illustrated in FIGS. 1 and 2, known molding techniques for creating such a bumper fascia 20 include a mold 22 with a cavity portion 24, a stationary core portion 26, and outwardly movable side cores 28 that mate with a corresponding section of the mold cavity to form the wheel well flanges 30. After molding, the movable side cores 28 are moved outward to a degree that temporarily deforms the fascia wings and permits the wheel well flanges 30 to clear the mold cores as the bumper fascia is ejected therefrom.
This known molding technique and mold design may adequately function to produce a bumper fascia with inwardly extending wheel well flanges. However, current molds and mold release methods do not include movable mold cores in the flange undercut on the fender cut line (or other body cut lines such as side-panel cut lines). As such, there is a point where a movable mold core helps disengage the wheel arch flange on the bumper fascia from the mold, but stops short of the flange undercut on the fender cut line. This mold and movable mold core arrangement lead to a substantial outward bending of the bumper fascia wheel well flange area in order to allow for mold clearance during part ejection. This has led to undesired permanent deformation of the bumper fascia, leading to higher scrap rates and lost time during vehicle production processes.
Accordingly, it should be apparent from the above remarks that it would be desirable to provide a mold and molding technique that enables movable mold cores to extend along a greater length of the wheel well flange, particularly into the flange undercut on the fender cut line (or other body cut lines). Such a mold and molding technique would eliminate and/or minimize undesired permanent deformation of the bumper fascia as the bumper fascia undercut areas are removed from the mold. The present disclosure provides such a mold and molding technique.